Matt Walker, BBC News 22 Jul 09;
The precarious status of the Bactrian camel has been highlighted by a new genetic study.
An analysis by scientists in China and Inner Mongolia shows that wild Bactrian camels are distantly related to their domestic two-humped counterparts.
That reinforces the idea that the few hundred remaining wild Bactrian camels are unique, and should be kept separate from those in domestic herds.
Bactrians are the last remaining wild camels of any type.
Bactrian camels ( Camelus bactrianus ) are huge animals that stand up to 2.3m tall at the shoulder and can weigh up to 690kg.
Fewer than 1000 wild Bactrian camels survive in just a few areas in north-west China and south-west Mongolia.
The animal is listed as critically endangered and the Zoological Society of London's EDGE of Existence programme ranks them among the 100 most evolutionarily distinct but globally endangered animals.
Domestic rival
Despite the tiny number in the wild, a significant number of domestic Bactrian camels are herded in the cold deserts in China and Mongolia.
However, the relationship between wild Bactrian camels and those kept domestically has been unclear.
The wild camels have smaller, more slender bodies with thinner, more lithe legs, and lower pyramid-shaped humps.
Recent research has also shown that the two find it difficult to interbreed.
To find out more about this relationship, Rimutu Ji of the Inner Mongolia Agricultural University in Huhhot, China, and He Meng of Shanghai Jiao Tong University, teamed up with scientists from the Chinese Academy of Sciences to sample the DNA of 18 domestic and three wild camels selected from different regions.
The researchers confirmed that the different groups of wild camel in Gansu, China and Govi-Altay, Mongolia are closely related, though they could not determine their common ancestor.
They also confirmed that all domestic camels originated from the same population.
However, domestic camels did not originate from the group of camels that still survive in the wild, say the researchers.
Separate entities
They found that the domestic and wild camels first diverged around 700,000 years ago.
The researchers cannot be sure, but they suspect that changes to the climate may have caused one group of Bactrian camels to migrate en masse away from the others, and that the ancestor of the domestic two-humped camel probably went extinct thousands of years ago.
That confirms what conservationists have long suspected: that the two groups are genetically unique, and must be considered to be distinct subspecies.
"The wild group is worthy of conservation as a separate entity," says Richard Kock, conservation programme manager for the Zoological Society of London.
"What is important is that the population needs to remain discrete and in a reasonably high number if it is not to be genetically swamped out by hybridisation with the domestic animal."
The wild one-humped dromedary camel ( Camelus dromedarius ) is already extinct, making the remaining wild Bactrians the last known wild camels.
